This invention relates generally to improvements in high intensity lighting equipment of the type used in television, motion picture and theatrical lighting applications for illuminating stage and studio sets, on-location scenes and the like. More specifically, this invention relates to an improved high intensity lamp holder of the type having a double ended lamp, wherein the improved lamp holder resiliently supports the lamp to prevent damage due to thermal stress, physical shock, vibration, and the like.
High intensity fixtures are generally known in the art for use in general lighting purposes in television, motion picture, and theatrical productions. Example of such high intensity lamps include gas vapor, arc, metal halide (HMI), or equivalent type, all of which commonly include a metal lamp housing having an appropriate high intensity lamp mounted therein. Such high intensity lamps are available in a variety of different sizes and power ratings, for example, on the order of 500 watts to 18 or more kilowatts. Such high intensity lamps are known to generate substantial quantities of heat energy during normal operation, with lamp surfaces typically exhibiting a temperature during normal operation on the order of about 600.degree. to 800.degree. C. (1100.degree. to 1500.degree. F.). These lamps produce large quantities of light, are relatively costly, and in one common form, are provided in a double ended geometry for connection of opposite ends to an appropriate electrical power supply.
In the past, double ended high intensity lamps have included an aligned pair of lamp holders having large and heavy ridged heat sinks, with limited tolerances that apply stress to the lamp, resist thermal expansion, restrict convection cooling, and do not isolate the lamp from physical shock. Such lamp holders were adapted for receiving and supporting a double ended lamp in a predetermined position within a lamp housing. The dual lamp holders are normally designed to securely position the lamp filament in front of a curved reflector, so that substantially all of the generated light will be projected forwardly from the lamp housing. However, during normal use, generated heat subjects the lamp structure to significant thermal stress which can contribute to premature bulb failure. Efforts to conduct heat through terminal convection from the lamp, and thereby reduce thermal stress, have involved relatively sophisticated heat sink structures incorporated into the lamp holders. Unfortunately, these heat sink structures increase the cost of the high intensity fixture and additionally require at least some disassembly to permit installation or removal of the double ended lamp.
Moreover, the dual sockets in prior double ended high intensity fixtures have not satisfactorily protected the fragile lamp against damage due to physical shock and/or vibration, particularly of the type encountered during transport to and from a filming site and/or in the course of moving the fixture to different positions on the set. To protect the fragile double ended lamp, it has been necessary to remove the lamp from the fixture prior to movement or transport, and to reinstalled the lamp when the fixture is positioned for use. Such lamp removal and reinstallation is undesirably time-consuming, and also involves substantial risk of damage attributable to manual mishandling.
The present invention provides an improved double ended high intensity fixture having an lamp holder for receiving and supporting the opposite ends of a double ended lamp, wherein the lamp is resiliently supported in a floating manner accommodating thermal stress and substantially isolating the lamp from shock and vibration.